Electronic retinas are being improved
Bionic eye restored sight to nine blind people
NewScientist news: New retinal implant gives sight to nine blind peopleThe implantable bionic retina partially restored vision to nine participants in clinical trials of the device.
The test results were published on February 20 in the journal Proceedings of the Royal Society B (Stingl et al., Artificial vision with wirelessly powered subretinal electronic implant alpha-IMS).
The device, called Alpha IMS and developed by specialists from the University of Tubingen (Germany) under the auspices of the Retina Implant AG company founded by them, became the second bionic retinal prosthesis created in recent years, which makes it easier for patients suffering from degenerative retinal changes due to a hereditary disease called Retinitis Pigmentosa. There are about one and a half million of them all over the world.
The first of them, Argus II, developed by the Californian company Second Sight Medical Products, was released to the EU market in March 2011, and in mid-February 2013 received approval from the US Food and Drug Administration (FDA). Both devices are intended exclusively for patients with retinitis pigmentosa, whose photoreceptor cells are destroyed, but the optic nerve is preserved, to which a signal is sent, which then enters the brain, as well as the neural layers of the retina. At the same time, the principle of operation of Alpha IMS and Argus II is different.
Argus II uses a processor to convert optical signals coming from a video camera mounted on a pair of glasses into electrical impulses, which then fall on a chip implanted in the retina with 60 electrodes connected to the optic nerve.
Alpha IMS works with optical signals coming directly to the retina, without the use of an external camera, which ensures free movement of the patient's eyes, while a patient with Argus II needs to turn his head there to look to the side, and also uses an optical eye apparatus.
Alpha IMS is a 1500-pixel microchip measuring three by three millimeters, implanted not in, but under the retina, which provides the best optical resolution. Each photosensitive pixel corresponds to a photodiode that analyzes the brightness of the light entering the eye, an amplifier and an electrode that transmits a signal to the nearby neural layers of the retina and to the optic nerve, thus completely simulating the work of photoreceptor cells. The brightness and contrast of the image is regulated by the patient himself using a battery-powered remote control that wirelessly communicates with an amplifier implanted subcutaneously behind the ear, which, in turn, is connected to the microchip by the thinnest cable.
Drawing from an article in the Proceedings of the Royal Society – VM
During clinical trials in May 2010, Alpha IMS was implanted into one of the eyes of nine German citizens (four women and five men) aged 35 to 62 years suffering from retinitis pigmentosa. During the observation period, which lasted from three to nine months, three of the previously completely blind patients were able to read individual letters, and one – signs of restaurants and shops. All test participants reported the appearance of the ability to recognize people's faces, the outlines of figures, to recognize various environmental objects, including moving cars. At the same time, patients did not have color vision, and in their visual impressions they were based only on differences in the intensity of light signals coming from objects.
Alpha IMS pilot tests took place from 2005 to 2010. The authors say that the newly obtained results exceeded their expectations and the results of the first tests. Currently, Alpha IMS trials are continuing, the device has been implanted in 36 patients in the UK and Hong Kong. Among them, according to The Daily Mail, the head of the British Paralympic Association, the multiple champion of the Paralympic Games in swimming Tim Reddish, who was finally able to consider his 50 medals. Due to retinitis pigmentosa, Raddish became completely blind 17 years ago.
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